FIRST HALF OF THE NINETEENTH CENTURY or ideas into which the objects known to us can be resolved do not depend on the nature of the soul, ** The soul is originally a tabula rasa in the most absolute sense, without any form of life or presentation: consequently, there are in it neither primitive ideas, not any predisposition to form them. All ideas, without exception, are a product of time and experience."* That being so, it is obvious that we must not think of the mind as evolving from within, but rather as being formed from without by contact with the world of men and things; and since this makes education a process of mind-forming by the supply and direction of experiences, it becomes important to have some idea of how the mind is actually made. Here the depictment of presentations as forces is helpful. A sound or a smell—to take the simplest of presentations—has a qualitative character of its own, but that can be ignored. The point is that, whatever more they are, all pre- sentations are like forces in that they appear, grow stronger or weaker, and gradually pass away as though their energy were spent. On this analogy each presentation or idea is to be regarded as a form of activity. Once it enters the soul, it is transformed into " a striving to present itself/' and in the absence of any competing presentation it rises at once above the threshold of consciousness. But at any one time there is usually a number of presentations all seeking attention, and whether any particular one will succeed in forcing its way into consciousness depends on the character of its competitors. Some presentations are contrary, and therefore mutually exclusive. Red and blue, for example, come into conflict when presented together. One or other is bound to dis- appear from consciousness and become a mere tendency to reappear under more favourable conditions. Other presentations are similar. When a presentation similar to others already in consciousness appears, a fusion takes place, which gives the new presentation a greater strength than it has as a unit. Others, again, are neither similar nor contrary, but simply disparate. Presentations of colour, shape and smell, for example, cannot fuse and they do not conflict; but they may form a complex or mass as when we have before our minds an object which is red and round and pungent. Here then we have in these varied relations of presentations the mechanism of the soul by which the systems of ideas that constitute the individual mind are made up. Herbart * Psychologic els Wissenscfaft, $ iao.